With increasing demands for greater miniaturisation and the use of flexible circuitry, the need for improved fabrication methods for high resolution printed circuit boards is becoming more important. PCBs currently include conductors as narrow as 150 µm, but there is now a requirement for conductors to be as narrow as 25 µm and even down to 10 µm.
With current manufacturing techniques, it is not possible to attain the required precision, especially where the spacing between the conductors varies. The etching rate is highest where the conductors are furthest apart. This leads to over-etching and subsequent under-cutting of these very fine conductors in these areas. The resultant PCB has copper conductors of variable width, and its performance is, therefore, not optimum.
By controlling the etch conditions and the area to be etched, the Oxford inventors have reduced the amount of over-etching to an acceptable level and under-cutting has been virtually eliminated. The spaces between the conductors are now all of uniform width, but with more redundant copper remaining on the PCB; the etching has been confined to narrow tracks.
This technology will benefit many of the applications that now demand PCBs with fine conductors or alternatively require flexible circuitry to facilitate yet further miniaturisation. Typically these include applications such as mobile phones, personal flip-top organisers and inkjet printers.
The invention itself is the subject of a patent application and companies interested in developing this technology commercially are invited to contact Isis Innovation.
For further information contact Dr David Eastham (Project Manager) david.eastham@isis.ox.ac.uk
Isis Innovation Ltd
Ewert House
Ewert Place Summertown
Oxford OX2 7BZ
Tel: +44 (0) 1865 272411
Fax: +44 (0) 1865 272412 Email: innovation@isis.ox.ac.uk
